In her ass

Her lack of expression didn't bother you during sex, but now that you're about to cum you feel a surge of anger over her lack of participation. You pull your dick out of her pussy, and using her juices as lube, you shove your cock all the way into her virgin ass.

That changes her expression. She rears up and a look of surprise and pain appears on her face. Her ass is so tight, you come immediately. She yelps and struggles against your penis. You finish filling her asshole.

"Next time, show a little more enthusiam, or I'll fuck your ass the whole time," you demand.

She doesn't say anything, but nods vigorously in response. You point to the bed and she clambers in, naked. You follow her in and snuggle up to her squishy body. You fall asleep cradling her warm, soft boobs.